Biology subjects

Fujii, C.

Publications and source records attributed to Fujii, C..

4 recordsLinked to original sources

bioRxiv2023

Massive RNA editing in ascetosporean mitochondria

Ascetosporeans are parasitic protists of invertebrates. As only two species of Mikrocytida, an ascetosporean subgroup, have ever been sequenced deeply and analyzed using cells isolated from infected organisms, it was shown that their mitochondria are functionally reduced and the organellar genome is lacking. However, molecular studies on other ascetosporeans have not been conducted, and whether reduced mitochondria is common in ascetosporeans remains unclear. In the present study, we established two cultures of Paradinida, another ascetosporean subgroup, and reconstructed their mitochondrial genomes. As they were compared with their RNA-seq data, massive A-to-I and C-to-U types of RNA editing were detected. Many editing sites are shared between two paradinids, but strain-unique sites also exist. As the mitochondrial genes are involved in the electron transfer system, their mitochondria are not functionally reduced, unlike that in Mikrocytida. Furthermore, we detected adenosine deaminase acting on RNA (ADAR), which is a key enzyme of A-to-I substitution, in paradinids as well as several other protists. Immunostaining showed that this ADAR is specifically localized in the mitochondria of paradinids, suggesting that A-to-I substitution in paradinid mitochondria is mediated by ADAR. These findings elucidated the functional diversity and evolutionary process of ascetosporean mitochondria as well as ADAR.

evolutionary biology↗

bioRxiv2023

The highly conserved stem-loop II motif is dispensable for SARS-CoV-2

The stem-loop II motif (s2m) is a RNA structural element that is found in the 3 untranslated region (UTR) of many RNA viruses including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Though the motif was discovered over twenty-five years ago, its functional significance is unknown. In order to understand the importance of s2m, we created viruses with deletions or mutations of the s2m by reverse genetics and also evaluated a clinical isolate harboring a unique s2m deletion. Deletion or mutation of the s2m had no effect on growth in vitro, or growth and viral fitness in Syrian hamsters in vivo. We also compared the secondary structure of the 3 UTR of wild type and s2m deletion viruses using SHAPE-MaP and DMS-MaPseq. These experiments demonstrate that the s2m forms an independent structure and that its deletion does not alter the overall remaining 3UTR RNA structure. Together, these findings suggest that s2m is dispensable for SARS-CoV-2. IMPORTANCERNA viruses, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) contain functional structures to support virus replication, translation and evasion of the host antiviral immune response. The 3 untranslated region of early isolates of SARS-CoV-2 contained a stem-loop II motif (s2m), which is a RNA structural element that is found in many RNA viruses. This motif was discovered over twenty-five years ago, but its functional significance is unknown. We created SARS-CoV-2 with deletions or mutations of the s2m and determined the effect of these changes on viral growth in tissue culture and in rodent models of infection. Deletion or mutation of the s2m element had no effect on growth in vitro, or growth and viral fitness in Syrian hamsters in vivo. We also observed no impact of the deletion on other known RNA structures in the same region of the genome. These experiments demonstrate that the s2m is dispensable for SARS-CoV-2.

microbiology↗

bioRxiv2022

The highly conserved stem-loop II motif is important for the lifecycle of astroviruses but dispensable for SARS-CoV-2

The stem-loop II motif (s2m) is an RNA element present in viruses from divergent viral families, including astroviruses and coronaviruses, but its functional significance is unknown. We created deletions or substitutions of the s2m in astrovirus VA1 (VA1), classic human astrovirus 1 (HAstV1) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). For VA1, recombinant virus could not be rescued upon partial deletion of the s2m or substitutions of G-C base pairs. Compensatory substitutions that restored the G-C base-pair enabled recovery of VA1. For HAstV1, a partial deletion of the s2m resulted in decreased viral titers compared to wild-type virus, and reduced activity in a replicon system. In contrast, deletion or mutation of the SARS-CoV-2 s2m had no effect on the ability to rescue the virus, growth in vitro, or growth in Syrian hamsters. Our study demonstrates the importance of the s2m is virus-dependent.

microbiology↗

bioRxiv2018

The recognition and expectations of ex-inpatients of mental health services: A web-based questionnaire survey in Japan.

Concern about mental health issues and the treatment of mentally disordered offenders attracts a lot of public attention. This study aimed to gather the experiences and opinions of people who have experienced admission to a psychiatric ward in order to understand their reaction to, and understanding of, the legislation behind the involuntary admission of psychiatric patients. A web-based questionnaire survey was conducted with a total of 379 participants, using a cross-sectional, exploratory design. The data were analyzed using a chi-square test, Fishers exact test, and a logistic regression analysis. According to the results, many patients were satisfied with their psychiatric admission, however, few participants said that they had been given adequate explanation for their involuntary treatment. Most participants expected qualified aids after discharge, although the prospect of a regular visit from an official was not entirely supported by the participants. Patient satisfaction was relevant to the discussion of their needs after discharge and in developing a crisis plan during admission. These findings suggests that psychiatric patients accept inpatient treatment as long as they receive an adequate explanation. More qualified care such as relapse prevention would be expected to lead to better satisfaction. In order for them to welcome regular visits from an official, patients may need more information and discussion.

neuroscience↗